MEDIUM-SIZED CYCLOPHANES .7. 4,14-DISUBSTITUTED [2.2]METACYCLOPHANES

The stereoselective syntheses of 4,14-dimethyl- and 4,14-dimethoxy [2.2] metacyclophanes have been achieved by the modified Wurtz dimerization reaction carried out under extremely mild conditions. A series of further 4,14-disubstituted [2.2] metacyclophanes have been derived from the dimethyl derivative 4. The nmr spectra of these compounds were examined in relation to the electronic and long-range effects of the substituents to the aryl and methylene signals. The chemical shift difference in protons meta to the substituent was correlated with Hammett σmconstant; -ρ6,12-H = 28.2 cps/σmand -ρs.16-H = 14.5 cps/σm. Whereas 1,2-methylene protons, especially those in the equatorial position, deviated largely, good linear relations were observed in 9,10-methylene absorption; -σ9,10-ax = 6.88 cps/ρpand -ρ9,10-eq = 14.4 cps/σp. © 1968, American Chemical Society. All rights reserved.